This analytical core laboratory will be housed at Lamont-Doherty Earth Observatory (LDEO) and will provide sample preparation and analyzes to five of the projects of this Superfund application (Project 1, Project 3, Project 5, Project 6, and Project 7). Sample preparation will include the following matrices: water, soil, sediment and pre-ashed blood. The instrumentation that will be used includes a VG sector 54-30 Thermal Ionization Mass Spectrometer (TIMS), a Hitachi Z8200 Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS), a VG High-Resolution ICP-MS. Analyses to be performed for Projects 1 include stable isotope ratios on pre-ashed blood samples and soil samples and total arsenic concentrations for soil samples. Analyses to be performed for Project 3 include concentrations of As in drinking waters. Concentrations and speciation of arsenic in water and sediment samples will be measured for Projects 5, 6, and 7, as well as concentrations of redox-sensitive elements (e.g., Sb, Fe, Mn, U, Mo, Cd) in the same matrices. In addition, radionucleotide measurements via gamma spectroscopy will be made on sediment cores for Project 6.